\documentclass{article}
%
% 数学环境支持
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{amsmath}
\usepackage{fancyhdr}
\pagestyle{fancy}
\lhead{\author}
\chead{\date}
\rhead{152 fuck}
\lfoot{}
\cfoot{\thepage}
\rfoot{}
\renewcommand{\headrulewidth}{0.4pt}
\renewcommand{\headwidth}{\textwidth}
\renewcommand{\footrulewidth}{0pt}
\begin{document}
Einstein 's $E=mc^2$.

\[ E=mc^2. \]
\[ z = r\cdot e^{2\pi i}. \]
\begin{equation}
E=mc^2.
\end{equation}
$\sqrt{x}$, $\frac{1}{2}$.

\[ \sqrt{x}, \]

\[ \frac{1}{2}. \]

$ \sum_{i=1}^n i\quad \prod_{i=1}^n $
$ \sum\limits _{i=1}^n i\quad \prod\limits _{i=1}^n $
\[ \lim_{x\to0}x^2 \quad \int_a^b x^2 dx \]
\[ \lim\nolimits _{x\to0}x^2\quad \int\nolimits_a^b x^2 dx \]



\[ \iint\quad \iiint\quad \iiiint\quad \idotsint \]



\[ \Bigg(\bigg(\Big(\big((x)\big)\Big)\bigg)\Bigg) \]
\[ \Bigg[\bigg[\Big[\big[[x]\big]\Big]\bigg]\Bigg] \]
\[ \Bigg \{\bigg \{\Big \{\big \{\{x\}\big \}\Big \}\bigg \}\Bigg\} \]
\[ \Bigg\langle\bigg\langle\Big\langle\big\langle\langle x
\rangle\big\rangle\Big\rangle\bigg\rangle\Bigg\rangle \]
\[ \Bigg\lvert\bigg\lvert\Big\lvert\big\lvert\lvert x
\rvert\big\rvert\Big\rvert\bigg\rvert\Bigg\rvert \]
\[ \Bigg\lVert\bigg\lVert\Big\lVert\big\lVert\lVert x
\rVert\big\rVert\Big\rVert\bigg\rVert\Bigg\rVert \]


\[ x_1,x_2,\dots ,x_n\quad 1,2,\cdots ,n\quad
\vdots\quad \ddots \]


\[ \begin{pmatrix} a&b\\c&d \end{pmatrix} \quad
\begin{bmatrix} a&b\\c&d \end{bmatrix} \quad
\begin{Bmatrix} a&b\\c&d \end{Bmatrix} \quad
\begin{vmatrix} a&b\\c&d \end{vmatrix} \quad
\begin{Vmatrix} a&b\\c&d \end{Vmatrix} \]


Marry has a little matrix $ ( \begin{smallmatrix} a&b\\c&d \end{smallmatrix} ) $.


\begin{multline}
x = a+b+c+{} \\
d+e+f+g
\end{multline}

\[\begin{aligned}
x ={}& a+b+c+{} \\
&d+e+f+g
\end{aligned}\]

\begin{gather}
a = b+c+d \\
x = y+z
\end{gather}
\begin{align}
a &= b+c+d \\
x &= y+z
\end{align}

\[ y=
\begin{cases}
-x,\quad x\leq 0 \\
x,\quad x>0
\end{cases} \]

\begin{tabular}{|l|c|r|}
 \hline
操作系统& 发行版& 编辑器\\
 \hline
Windows & MikTeX & TexMakerX \\
 \hline
Unix/Linux & teTeX & Kile \\
 \hline
Mac OS & MacTeX & TeXShop \\
 \hline
通用& TeX Live & TeXworks \\
 \hline
\end{tabular}

\end{document}